Various types of motors are partially or wholly encapsulated within a material to help hold its component parts together. The particular material employed to encapsulate the motor may vary depending on the intended application of the motor. In addition, different encapsulation techniques also may be used for different types of motors.
One particular type of motor is a linear motor, such as may include stationary armatures that contain coils and movable stages containing magnets. Alternatively, linear motors can have stationary magnets and moving coils. When the windings are powered, armature heating occurs. The maximum allowable temperature for the armature windings, for example, limits the maximum force obtainable from a linear motor.
Linear motors are increasingly being employed in manufacturing equipment. In such equipment, nominal increases in the speed of operation translate into significant savings in the cost of production. Accordingly, it is often desirable to produce as much force and acceleration as possible in a given linear motor. An increase in force, however, requires either an increase in magnetic field intensity or an increase in current applied to coils of the armature. In a permanent magnet linear motor, for example, the available magnetic field intensity is limited by the field strength of available motor magnets. Power dissipated in the coils generally increases at a rate equal the square of the current. Attendant heat generation tends to limit the force that may be achieved without exceeding the maximum allowable armature temperature.
In a typical linear motor system, the armature assembly includes a coil disposed within a core, such as may be formed of a lamination stack of an electrically conductive material. An epoxy block, for example, is applied via an epoxy mold to encapsulate the armature assembly, which includes a coil and laminated stack. By way of illustration, epoxy is molded around the armature assembly within a mold, which may take upwards of forty-five minutes to sufficiently cure. The encapsulated armature assembly is removed from the mold and trimmed, which trimming may include grinding of part of the epoxy. The mold is then cleaned in preparation of the next molding operation. A typical epoxy molding process thus requires significant time and handling, which tends to increase manufacturing cost.